1. Field of the Invention
The present invention relates to a method for producing noodles that includes adding transglutaminase and gliadin or glutenin to the dough mixture to enrich the taste, glutinosity and elasticity of the noodles produced. The noodles include, for example, Japanese wheat noodles, udon, soumen and hiyamugi made from wheat flour; Japanese buckwheat noodles, soba made from buckwheat flour; Chinese wheat noodles and coating of won-tons, shao-mais, jiaozies and the like made from wheat flour to which is added an alkali agent such as edible potassium carbonate; and spaghetti, macaroni and the like made from durum wheat flour. Noodles produced according to the method of the invention taste good and their glutinosity and elasticity last for a long period of time.
2. Description of the Related Art
Noodles include Chinese noodles, Japanese noodles of soba and udon, the coating of won-tons, shao-mais, jiaozies, and crispy spring rolls. These are sold in the market after having been processed to improve storability, for example, retorted, frozen, dried or semi-dried and acid-processed. Noodles should have a glutinous taste when eaten. However, the acid-processed or retorted noodles often lose the original taste and glutinosity of non-processed raw noodles. The processed noodles should have, after having been boiled, an elastic and especially glutinous taste for a long period of time.
Various improvements have been made in the field of processed noodles. For example, Japanese Patent Kokai 119151/1986 discloses a technique of adding vinegar along with seaweed extract, locust bean gum, guar gum, xanthane gum or the like to noodles. Japanese Patent Kokai 283547/1988 discloses a technique of coating boiled noodles with gelatin to protecting them from being non-glutinous and ensuring their good original shape. Japanese Patent Kokai 117353/1990 discloses a technique of adding a proteinaceous material, starch or the like along with active gluten, soybean protein, egg white, whole egg, casein, emulsifier, polysaccharide or the like to noodles. Japanese Patent Kokai 105662/1994 discloses a technique of adding a fraction from wheat consisting essentially of gliadin along with an ordinary noodle modifier such as egg white to noodles thereby improving the storability and processability of noodles. Japanese Patent Kokai 153832/1994 discloses a technique of adding a wheat fraction consisting essentially of glutenin to noodles to produce improved LL (long life) noodles. However, these techniques do not produce tasty noodles which can be stored for a long period of time, and further improvements in producing processed noodles are required.
Japanese Patent Kokai 105662/1994 and Japanese Patent Kokai 153832/1994 disclose a technique of using a gliadin fraction from wheat in producing noodles, in which the wheat fraction consisting essentially of gliadin is, along with egg white powder and other protein, added to noodles to improve the elasticity and glutinosity of the noodles. However, the noodles produced according to this technique were not satisfactorily elastic, stiff and glutinous, and inevitably become non-glutinous when boiled. Even though processed according to the disclosed technique, LL noodles that require heating and acid-processing after having been boiled lose their elasticity.
Apart from the techniques noted above, various methods of improving noodles with transglutaminase are known that do not satisfy the recent demand for elastic and glutinous noodles. In particular, if transglutaminase is added to processed noodles such as acid-processed noodles, retorted noodles and frozen noodles, these noodles easily lose their elasticity and glutinosity. Therefore, further improvements are required in adding transglutaminase to noodles.
Chinese noodles require toughness, elasticity and glutinosity, while Japanese udon noodles require elasticity and high glutinosity. More improvements in producing Chinese and Japanese noodles are required.
Transglutaminase is effective in stiffening noodles, since it acts on gluten in wheat flour to promote the crosslinking of gluten. As a result, transglutaminase can enhance the elasticity and glutinosity of noodles. However, the crosslinking network structure of gluten responsible for the strong elasticity and glutinosity of noodles that contain the crosslinked gluten is damaged when the noodles are processed with acid or retorted. As a result the noodles become rough and brittle and lose their intrinsic elasticity and glutinosity, and thus the noodles have an unpleasant taste.
The object of the present invention is to provide a method for producing noodles in which the noodles have improved elasticity, glutinosity and taste, and maintain their improved characteristics for a long period of time. Even when acid-processed, retorted and/or frozen, the noodles produced by the method of the invention maintain the good taste characteristics, toughness, stiffness and glutinosity for a long period of time.
Means for Solving the Problems
We, the present inventors have assiduously studied in order to attain the object, and, as a result, have found that when a combination of transglutaminase and gliadin or glutenin is added to noodles, the glutinosity and elasticity of the resulting noodles is improved. In particular, dry Japanese noodles according to the invention are not softened too much by drying and are much more glutinous. Thus, the dry noodles are tasty when boiled and eaten, like raw noodles. In acid-processing, retorting and/or freezing, Chinese noodles according to the invention do not lose their intrinsic taste yet are tough, elastic and glutinous for a long period of time. On the basis of these findings, we have completed the present invention.
Accordingly, the first embodiment of the present invention relates to a method for making noodles that includes:
adding transglutaminase, and
at least one of either gliadin or glutenin to a dough mixture that includes cereal.
The second embodiment of the present invention relates to a dough mixture that includes transglutaminase, at least one of either glutenin or gliadin, and cereal.
The third embodiment of the present invention relates to a noodle produced by a process that includes adding transglutaminase and at least one of either gliadin or glutenin to a dough mixture that includes cereal.
The fourth embodiment of the present invention relates to a composition that includes transglutaminase and at least one of either glutenin or gliadin.
Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description, which is not intended to be limiting unless otherwise specified.
The invention relates to the improvement in producing noodles from cereals and other side materials, which is characterized by adding transglutaminase along with gliadin or glutenin to the materials of noodles.
Transglutaminase is an enzyme for catalyzing the acyl transfer reaction of the xcex3-carboxyamide group of the glutamine residue in the peptide chain of wheat gluten. Acting as an acyl receptor on the xcex5-amino group of the lysine residue in protein, transglutaminase gives intramolecular and intermolecular xcex5-(xcex3-Glu)Lys bonds to protein molecules.
Transglutaminase may be either calcium-independent or calcium-dependent, any of which is usable in the invention. As examples of the former, mentioned are those derived from microorganisms (see, for example, Japanese Patent Kokai 27471/1989), the entire contents of which are hereby incorporated by reference. As examples of the latter, mentioned are those derived from guinea pig liver (see Japanese Patent Koukoku 50382/1989), fish-derived ones (see, for example, N. Seki et al""s xe2x80x9cJournal of the Fisheries Society of Japanxe2x80x9d, Vol. 56, pp. 125-132, 1990; and xe2x80x9cPreprint of ""90 Spring-term Discussions and Lectures in the Fisheries Society of Japanxe2x80x9d, page 219), and factor XIII existing in blood, etc. (see WO93/15234), the entire contents of each of which are hereby incorporated by reference. Apart from those, further mentioned are transglutaminases produced by genetic recombination (see Japanese Patent Kokai 300889/1989, Japanese Patent Kokai 199883/1993, Japanese Patent Kokai 225775/1994, and EP-0693556A) the entire contents of each of which are hereby incorporated by reference. Any of such transglutaminases is employable in the invention, without being limited by the sources and the production methods. Of those, however, preferred are calcium-independent ones in view of their functions for use in foods and of their economical aspects.
The amount of transglutaminase to be added is not particularly limiting and may be any ordinary one that is generally added to noodles for improving them. Preferable amounts may be from 0.1 to 100 units, but more preferably from 0.5 to 30 units, relative to 1 g of the protein content of the cereals. These ranges include all values and subranges therebetween. If the amount is smaller than the defined range, transglutaminase may be ineffective in improving the taste of noodles and in preventing the properties of noodles from being worsened during acid-processing or retorting. If so, the acid-processed or retorted noodles may be too soft. If the amount of the enzyme added is larger than the defined range, the taste of noodles may be worsened, and the noodles may be too tough.
Gliadin and glutenin are not particularly limiting and are referred to hereinunder. These are ethanol fractions from wheat gluten. Gliadin is a relatively small spherical protein having a molecular weight of from 30 kD to 80 kD, and this contributes to the glutinosity of noodles. In the invention, usable is any commercially-available gliadin, such as xe2x80x9cGlia Axe2x80x9d and xe2x80x9cGlia AGxe2x80x9d sold by Asama Chemicals Company. Any one as prepared from wheat gluten by known methods is also usable.
Glutenin is a thin fibrous protein having a molecular weight of from 200 kD to millions, and this contributes to the elasticity of wheat products. For this, usable is any commercially-available product, such as Asama Chemical""s xe2x80x9cGlute 100xe2x80x9d. Any one prepared from wheat gluten by known methods is also usable. Ethanol extraction of gliadin and glutenin from wheat protein is disclosed in, for example, xe2x80x9cJournal of the Food Industry Association of Japanxe2x80x9d, Vol. 38, p. 477, 1991, the entire contents of which are hereby incorporated by reference. Briefly, gliadin and glutenin may be extracted from dough of soft flour or hard flour. These may be electrophoretically confirmed in Laemmli""s SDS polyacrylamide gel electrophoresis (SDS-PAGE).
Japanese Patent Koukoku 37270/1974, the entire contents of which are hereby incorporated by reference, discloses a method for producing gum analogs through light thermal denaturation of wheat gluten. Baked gliadin as produced by this method is also usable in the invention. Molecules of baked gliadin have an enlarged hydrophobic area in their surface, while keeping their intrinsic properties. Therefore, baked gliadin acts favorably on noodles and improves their elasticity and glutinosity. Any ordinary baked gliadin is usable in the invention.
The amount of gliadin to be added is not particularly limiting and may be from 0.01 to 30.0% but is more preferably from 0.1 to 20.0%, relative to 100 g of the cereals. These ranges include all values and subranges therebetween. Unless otherwise specifically indicated, xe2x80x9c%xe2x80x9d referred to herein is by weight. If the amount is smaller than the defined range, the noodles may be. too tough and rough; but if it is larger than the same, the noodles may be too soft.
The amount of glutenin to be added is not particularly limiting and may preferably be from 0.01 to 30% but is more preferably from 0.1 to 25%, relative to 100 g of the cereals. These ranges include all values and subranges therebetween. If the amount is smaller than the defined range, the noodles may lose their intrinsic, smooth and glutinous taste. However, if it is larger than the defined range, the noodles may be too tough and brittle.
The cereal is not particularly limiting and may be any one ordinarily used in the art. Preferred examples include essential cereals such as rye flour, rice flour, soybean flour, soft flour, buckwheat flour, wheat flour, medium flour, hard flour, medium wheat flour, semi-hard wheat flour, durum semolina flour, and durum wheat flour, and mixtures thereof.
Egg white, processed starch and viscosity-increasing polysaccharides that are generally added to noodles are usable in the invention, without being specifically defined, so far as they do not interfere with the object of the invention. Their amounts are not specifically defined but may be any ordinary ones generally added to noodles.
In the invention, a composition that includes transglutaminase and gliadin or glutenin and optionally contains egg white, processed starch and viscosity-increasing polysaccharides may be added to the starting materials of noodles. Herein the invention provides a composition for producing noodles, which includes transglutaminase and gliadin or glutenin.
In carrying out the invention, transglutaminase and gliadin or glutenin are added to ordinary starting materials of noodles to make a dough mixture. If desired, any one or more of partial hydrolysates of protein, such as those of wheat protein, those of soybean protein, those of milk protein and those of gelatin, and other various proteins, such as milk protein, soybean protein and wheat protein, may be added to the dough mixture. Water and other ingredients may be added to and kneaded with the cereals such as wheat flour to prepare dough, during which step predetermined amounts of transglutaminase and gliadin or glutenin are added. The thus-kneaded dough may then be directly or after having been compounded and rolled, kept at a temperature between 0xc2x0 C. and 650xc2x0 C., preferably between 10xc2x0 C. and 55xc2x0 C., for a time of preferably 15 minutes to 24 hours, more preferably 50 minutes to 20 hours thereby making the enzyme, transglutaminase fully exhibit its enzymatic activity. These ranges include all values and subranges therebetween. During this aging, the enzyme, transglutaminase expresses its function.
Of the noodles produced by the method of the invention, non-processed raw noodles can be directly distributed in the market. If desired, the raw noodles may be boiled or steamed prior to being distributed. Also, the boiled or steamed noodles may be packaged and distributed. Also if desired, the raw noodles may be dried or semi-dried prior to being distributed. The boiled noodles may be processed with acid by dipping them in an acidic solution, or they may be retorted. The thus acid-processed or retorted noodles may then be distributed. Irrespective of their final forms mentioned above, the noodles produced by the method of the invention are elastic and glutinous and have a good taste all the time.
The activity unit of transglutaminase as referred to herein is defined and measured as follows. The enzyme is reacted with substrates of benzyloxycarbonyl-L-glutaminylglycine and hydroxylamine, then the resulting hydroxamic acid is formed into its iron complex in the presence of trichloroacetic acid, and the absorbance of the complex is measured at 525 nm. Based on the amount of the hydroxamic acid, a calibration curve is prepared, on which the enzymatic amount of transglutaminase capable of producing 1 xcexcmol of hydroxamate within one minute is calculated. This is the activity unit, one unit of the enzyme, transglutaminase. For this, referred to is Japanese Patent Kokai 27471/1989, the entire contents of which are hereby incorporated by reference.